In environments where food is prepared and cooked in a central location and distributed and served to consumers who are remotely located, such as in hotels, aircraft and institutional settings such as hospitals and nursing homes, there is often a delay between the time that the food is prepared, cooked and subsequently placed on a plate or other serving dish, and the time that the food is eventually presented to the consumer for consumption at a remote location. Accordingly, by the time the food is presented to the consumer, the food can become cold unless special measures are taken to keep the food hot. Various approaches have been employed by delivery system manufacturers in an effort to solve the problems associated with remote delivery of meals, sometimes referred to as "satelliting."
U.S. Pat. No. 5,611,328 to McDermott discloses a heat retentive service base that is inductively heated. The McDermott patent discloses a heat retentive service base formed by insert molding. In the McDermott insert molding process, the heat retentive core is held in the molding position by several pins. The pins are received in apertures disposed in the core. While the core is held in place, the liquid plastic is introduced around the core to form the service base. A central bore in the core holds the core in place and allows the liquid plastic to flow to the back side of the core for encasing the core within the service base and form a wall that becomes the service base bottom. Thereafter, the pins are removed from the service base. Plastic plugs that fit into the core and base apertures are ultrasonically welded to the bottom of the base.
One disadvantage of the McDermott base results from the need for high heat resistant plastic for the formation of the entire outer plastic portion of the base. Such high heat resistant plastic, such as a Radel.RTM. or Ultem.RTM., are substantially more expensive than most polypropylene plastics.
U.S. Pat. Nos. 5,603,858 and 5,786,643 to Wyatt et al. (hereinafter "the Wyatt et al. patents"), the disclosures of which are incorporated herein in their entirety, disclose a transportable heat retentive server that is adapted to be inductively heated. According to the Wyatt et al. patents the heat retentive server has central dish receiving portion that has an annular opening at its periphery between its upper and lower generally disk-shaped members. This Wyatt et al. server also has an outer peripheral member that has a hooked-shaped member that is received in the annular opening between the upper and lower generally disk-shaped members.
It has been found that the plastics used to form certain prior art inductively heated heat retentive servers exhibit degradation due to repeated exposure to chemicals, such as surfactants, used during the warewashing rinse cycle. As a result, such heat retentive servers exhibit cracking in the exterior, which allows water to compromise the interior of the heat retentive server. Such water-compromise can be particularly dangerous due to the rapid heating of the base achieved by induction heating. Water that compromises the interior and comes into intimate contact with the ferro-magnetic heat retentive disk rapidly vaporizes upon induction/activation causing in some cases the heat retentive server to explode.
One novel solution to the above-described compromise of the interior of the heat retentive server is described in copending application Ser. No. 08/892,059 (Wyatt) for Pressure Relief System for Inductively Heated Heat Retentive Server, the disclosure of which is incorporated herein as if set forth in its entirety. However, the pressure release valve adds significantly to the cost of manufacturing a heat retentive server. In addition to the cost of the parts, each pressure release valve must be tested after the valve has been incorporated into the heat retentive server. The additional time and labor adds significantly to the cost of manufacturing the heat retentive server. In addition, the pressure release valve only provides a safety mechanism in the event that water compromises the interior of the heat rententive server. While such a safety mechanism is important, ideally, it is preferable that water is prevented from compromising the interior of the heat retentive server in the first place.
There remains a need for a heat retentive server that (1) is susceptible to rapid heating through induction, (2) provides improved resistance to water-leakage into the interior of the serving base, (3) is forgiving if accidentally stacked one upon another after having been heated, (4) is lighter in weight, and (5) has a lower manufacturing cost than prior art inductively heated heat retentive servers. The present invention also provides many additional advantages, which shall become apparent as described below.